Lecture 1

Database Systems

Made up of 3 main elements:

  • Schema - design
  • DBMS - hosts data efficiently and robustly
  • Query Language - simple programming language

A database is needed if:

  • Lots of valuable data
  • Needs stored safely
  • Structured data and linked
  • Needs accessed efficiently

Technical Definition

Software and hardware system to manage storage and retrieval of large sets of structured data

7 Commandments of Databases
1. Thy data must be correct and consistent
2. Though shalt avoid redundancy and repeition
3. Though shalt not waste space
4. Each table shalt correspond to a thing in the world
5. Thy information must be uniquely identifiable
6. Thy database searches shall be fast and reliable
7. Thou shall not change thy database design after it goes live.

Every row must have a unique identifier within a table. A foreign key is a primary key in another table. A schema is an abstract structure of the tables in a database.